Torsional oscillator



p 1945- I B. E. EISENHOUR 2,384,823

TORSIONAL OSCILLATOR 7 Filed Feb. 8,1943 2 Sheets-Sheet 1 w Z I 21 .35 25 2? gar /lizfewzm @0224 fizz n,-

TORSIONAL OSCILLATOR Filed Feb. 8, 1943 2 Sheets-Sheet 2 five/$2 Ea 13. 2298205080.

Patented Sept. 18, 1945 TORSION AL OSCILLATOR Bert E. Eisenhour. Aurora, Ill., asslgnor of onehalf to Riverbank Laboratories, Geneva, Ill., a corporation of. Illinois Application February 8, 1943, Serial No. 475,187' 16 Claims. (01. 84-457).

The present invention relates to oscillators, and particularly to the torsional vibratory type. It has reference especially to an oscillator having a given or set frequency of vibration which is maintained constant for that setting or adjustment irrespective or regardless of the temperature or changes of temperature of the device. The period or frequency value can be made any value within the limits of the elastic coefficients of the material used. An important feature of the inventionis the use'of segments of metals having opposite values of temperature coeflicients of elasticity which when proportioned in accordance with said coefficients and adjustably fixedat predetermined noda] points will maintain a constant given frequency of vibration or oscillation of the device for different temperature conditions.

In my Patent No. 1,880,923 issued October 4, 1932, on a Compensated tuning fork, I disclose a tuning fork made up of laminations of metal having positive and negative temperature coefficients of elasticity so proportioned that the fork will have a given and maintained vibration frequency which will be constant'under changes of temperature of the fork. Once such a fork has been made to have a fundamental frequency, it remains with it, and when it is desired to use a fork with another given fundamental frequency of vibration, it has been found more practical to construct another fork for such purpose than to make adjustments in a fork already produced for some already given fundamental frequency, as by changing the proportions of the laminations used in making up the previously produced fork.

Among the objects of the present invention is to provide a novel oscillating means of th torsional vibratory type, and it comprises, by way of illustration, a mass, such as a disk of nonmagnetic metal, secured to the torsional element, such as a shaft or rod, at one point thereof which is free to move, as angularly, while another point thereof, as at an end thereof, is held fixed.

More particularly, the disk may be secured to an intermediate point of the rod while the end portions of the rod are held clamped in fixed posi-' tion. Th oscillations of the mass are angularly about the axis ofthe shaft or the longitudinal center of the torsional element.

Other objects, capabilities, advantages, features, and the like are comprehended by the invention as will later appear and as are inherently possessed by the invention.

Referring to the drawings:

Fig. 1 is a top plan view of the device constructed in accordance withthe invention;

Fig. 2 is a side elevatlonal view thereof; a

Fig. 3 is a transverse sectional view taken in a plane represented by line 33 in Fig l'of the" drawings; k

Fig. 4 is a fragmentary sectional view taken in a plane represented by line 4-4 in Fig. 3 of the drawings; 1 f

Fig. 5 is a transversesectional view of an alternateform of part of the device; v p

Fig. 6 is a transverse sectional view takenin a plane represented by line 6-6 in Fig. 5 of' the drawings; and, p V Fig. '7 is a part elevational view showing the. mode of holding the oscillating feature.

Referring more in detail to the drawings, the embodiments selected to illustrate the invention are shown as comprising a suitable support having posts I 0 and II the upper ends-of which have datum plane surfaces I2 and 13 serving as level. supports for the oscillating or. vibrating feature. of the invention, otherwise more fully, described herein. To the posts l0 and II is secured a sup.- porting plate M for adjustably supporting solenoids l 5 and IS the vertical heights of which may be adjusted by any suitablefmean's, such as screws I1 and I8 threaded through a the plate I4, as shown in Fig. 2. If desired springs 19 and",

may be interposed betweenthe plate l4- and,

the solenoids l5 and IS. The solenoids may have elongated cores.2l and. 22" as shown in Figs.

1 and 2. To the upper ends of the posts lfland I I are connected clamping plates 23, and 24 by way of screws 25 and 26 threadedinto the upperends'. ofthepostslfl and. p

The torsional oscillating device of the invention comprises a disk-like mass 21 'of .nonmagnetic material having an opening in which fits with a tight fit a collar or. bushingn-ln which in turn fit with a tight fit theinner ends of shaft-like segments-29 and 30 of the torsional element. These segments 29 and 30V shown in Figs. 1 to 4 inclusive are shown as round or rounded, but may be of any other desired crosssectional form. In Figs. 5, 6 and 7, theshaft is shown of rectangular cross sectlonand as comprising laminations 3| and 32 as elongated'segments, and the collar or bushing 33 in' the-disk 21 has a rectangular hole for the fitting therein with a tight fit of an intermediate portion of the shaft 3|-32.

The outer end portions 29 and 30 of the shaft shown in Flgs.- 1 to 4 inclusive are clamped in split collets 34 and 35 which are clamped between the clamping plates 23 and 24, and the surfaces 12 and iii of the posts Ill and II, and the outer end portions of the shaft or bar 3l--32 shown in Figs. 5, 6 and '7 are clamped in split collets 36 and 31 which are clamped between the clamping plates 23 and 24 and the surfaces [2 and [3 of the posts I and II.

Suitably fixed to the disk 21, as at opposite peripheral points thereof, are armatures 38 and 39, of any desired form, but, as'shown, may have heads to span the cores 2! and 22 of the solenoids. These armatures 38 and 39 are of magnetic material and are normally spaced from the cores 2| and 22 for clearance for oscillatory or vibratory movement of the disk 21 and the armatures 38 and 39 carried by it.

The segments or component parts of th torsional element may be composed on the one hand of any one of the various metals known as stoic metals, such as elinvar (invar, and other iron and nickel alloys), or chrome nickel with iron alloy, as steel, having the property of increasing and decreasing their elasticity or stiffness upon increase and decrease in temperature respectively, and on the other hand of such substance as carbon steel or any material in which an increase and decrease of temperature causes a decrease and increase respectively of elasticity or stiffness. The physical proportioning of the components, as in length, and diameter, may be made by trying out or testing so as to effect the change in one which will be equal to that in the other as a resultant for the device as a whole. Variations axially are made to change the frequency and also the temperature coefficient by moving the relation of the clamping collets at the ends of the shaft and the collet in the mass disk.

The present invention is a generator of electrical impulses and does not require an external force of vibrations to maintain it in oscillation but is connected to a source of power supply which is non-oscillatory. The instrument itself regulates this power to maintain itself in operation at its fundamental frequency.

The torsional oscillator of the present invent is a u des ed to vibrate at a specified frequency and to maintain that frequency to within a predetermined accuracy over a given range of temperature.

The oscillator can be maintained in oscillation by any of the conventional electric circuits in which the movement of an armature in a magnetic field generates current which, imposed on the grid of a vacuum tube, can govern the output of the plate of the tube to activate another electromagnet with a phase difference of substantially 180", thereby maintaining the oscillations. The primary purpose of an oscillator of this kind is to measure small intervals of time with a high degree of accuracy. The balance wheel in a watch is an oscillator but it has a period or frequency of but four, five or six oscillations per second. Many industrial applications of oscillations require frequencies from sixty vibrations per second to many thousand vibrations per second.

By taking a small part of the oscillator output, and by suitable amplification, sufficient power can be had to drive small synchronous motors such as used in transmission of pictures by radio, and by wire, facsimile, radar, and many other applications. This same method may be used in governing or controlling the frequency of cients of elasticity for giving the oscillator a power generating systems, as generating millions of hydro-electric power units with deviations in frequency of less than one second per month.

A tuning fork can be operated in a horizontal or vertical position and must be operated in the position in which it was calibrated. Many recent applications of oscillators require that they operate under conditions where they are subjected to violent external forces, as encountered in naval vessels, tanks, and airplanes, etc. The

frequency of a tuning fork will be affected by any sudden movement due to the relatively large mass and inertia of the vibrating parts. The torsional oscillation of the present invention is not subject to any of these objections as it is constructed to operate in any position and is not affected by violent motion that would seriously affect a fork.

A tuning fork, or a torsional oscillator, when properly mounted, will have a natural period of oscillation when excited as by striking or by any conventional method and will continue in oscillation for some time depending upon the damping.

The so-called damping of an oscillating mass consists primarily in molecular friction generating heat, and principally, in the case of a tuning fork, in alternate compressing and rarifying the air in contact with the prongs. The effect on the frequency of a tuning fork for a change of one inch of mercury in barometric pressure, is five parts per million. This is particularly objectionable for instruments in use in planes where the pressure changes between that at the surface of the earth at low altitude and that at high altitudes are customary and rapid. The design and shape of the oscillating element in the torsional oscillator of the present invention does not comprem or rarify the air and, therefore, is affected only by the change in viscosity due to change in pressure and is, therefore, small as compared to the air damping of a tuning fork.

While I have herein described and upon the drawings shown a few illustrative embodiments of the invention, it is to be understood that the latter is not limited thereto but may comprehend other constructions, details, arrangements of parts, and features, without departing from the spirit of the invention.

Having thus disclosed the invention, I claim:

1. An oscillator of the torsional type, comprising an elongated torsional element composed of longitudinally extending segments of metal having opposite values of temperature coefficients of elasticity for giving the oscillator a given frequency of oscillation for different temperature conditions at a given adjustment of the element, an oscillating mass secured to a free part of said element and extending radially therefrom to oscillate about the axis of said element, a stationary support, and means on said support for longitudinally adjustably securing in fixed position another part of said element.

2. An oscillator of the torsional type, comprising an elongated torsional element composed of longitudinally extending segments of metal having opposite values of temperature coeffigiven frequency of oscillation for different temperature conditions at a given adjustment of the element, an oscillating mass secured to a free part of each of said segments and extending radially therefrom to oscillate about the axis of said element, a, stationary support, and means perature conditions at a given adjustment of,

theelement, an oscillating mass of disk-like form secured to a free part of said element and extending radially therefrom to oscillate about the axis of said element, a stationary support, and means on said support for longitudinally adjustably securing in fixed position a part of said element remote from said mass.

4. An oscillator of the torsional type, comprising an elongated torsional element composed of longitudinally extending segments of metal having opposite values of temperature coefficients of elasticity for giving the oscillator a given frequency of oscillation for different temperature conditions at a given adjustment of the element, an oscillating mass secured to an intermediate portion of said element and extending radially therefrom to oscillate about the axis of said element, a stationary support, and means on said support for longitudinally adjustably fixing an end portion of said element.

5. An oscillator of the torsional type, comprising an elongated torsional element composed of longitudinally extending segments of metal having opposite values of temperature coefficients of elasticity for giving the oscillator a given frequency of oscillation for different temperature conditions at a given adjustment of the element, an oscillating mass extending radially from an intermediate portion of said element and secured to said segments, a stationary support, and means on said support for longitudinally adjustably fixing an end portion of said element.

6. An oscillator of the torsional type, comprising an elongated torsional element composed of longitudinally xtending segments of metal having opposite values of temperature coefficients of elasticity for giving the oscillator a given frequency of oscillation for different temperature conditions at a given adjustment of the element, a disk-like form of non-magnetic mass secured to an intermediate portion of said element and extending radially therefrom to oscillate about the axis of said element, a stationary support, and means on said support for longitudinally adjustably fixing an end portion of said element.

7. An oscillator of the torsional type, comprising an elongated torsional element composed of longitudinally extending segments of metal having opposite values of temperature coefllcients of elasticity for giving the oscillator a given frequency of oscillation for different temperature conditions at a given adjustment of the element, a disk-like form of non-magnetic mass secured to an intermediate portion of said element and extending radially therefrom to osci1-' late about the axis of said element, said mass having a radially extending magnetic armature, a stationary support, and means on said support for longitudinally adjustably fixing an end portion of said element.

8. An oscillator of the torsional type, comprising an elongated torsional element composed of longitudinally extending segments of metal having opposite values of temperature coefficients of elasticity for giving the oscillator a given frequency of oscillation for different temperature conditions at a given adjustment of the element, an oscillating mass secured to an intermediate portion of said element and extending radially therefrom, a stationary support, and means on said support for longitudinally adjustably fixing the end portions of said element at given points on said support for establishing the frequency fundamental of vibration of said element and maintaining it constant.

9. In an oscillator of the torsional type, a torsional element therefor, comprising an elongated shaft having substantially uniform cross-sectional area throughout the length of the shaft, and composed of segments of which one segment has a positive temperature coefficient of thermoelasticity and the other segment has a negative temperature coefficient of thermo-elasticity, means for holding said shaft for oscillation about an axis extending collinearly of said shaft, and a body connected to said shaft to oscillate with said shaft about said axis.

10. In an oscillator of the torsional type, a torsional element therefor, comprising an elongated shaft having substantially uniform cross-sectionaal area throughout the length of the shaft, and composed of segments of which one segment has a positive temperature c0efliicient of 0 thermo-elasticity and the other segment has a negative temperature coemcient of thermoelasticity, said segments having various ratios of lengths according to the positive and negative characteristics thereof, means for holding said shaft for oscillation about an axis extending collinearly of said shaft, and a body connected to said shaft to oscillate with said shaft about said axis.

11. In an oscillator of the torsional type, a torsional element therefor, comprising an elongated shaft having substantially uniform crosssectional area throughout the length of the shaft, and composed of segments of which one segment has a positive temperature coefficient of thermoelastioity and the other segment has a negative temperature coefficient of thermo-elasticity, said shaft being round in cross section, and the seeinents thereof having different diameters according to the positive and negative characteristics thereof, means for holding said shaft for oscillation about an axis extending collinearly of said shaft, and a body connected to said shaft to oscillate with said shaft about said axis.

12. In an oscillator of the torsional type, a torsional element therefor, comprising an elongated shaft having substantially uniform crosssectional area throughout the length of the shaft, and composed of segments of which one segment has a positive temperature coefficient of thermo-elasticity and the other segment has a negative temperature coefficient of thermoelasticity, said shaft being of polygonal cross sectional form with the segments thereof also of polygonal cross sectional form, means for holding said shaft for oscillation about an axis extending collinearly of said shaft, and a body connected to said shaft to oscillat with said shaft about said axis.

13. In an oscillator of the torsional type, a torsional element therefor, comprising an elongated shaft having substantially uniform crosssectional area throughout the length of the shaft, and composed of segments of which one segment has a positive temperature coefficient of thermo-elasticity and the other segment has a negative temperature coefijcient of thermol s ic s s a t, be n Qt po y ona Cross sectional form with, the segments thereof also of polygonal cross sectional torm, the cross sectional areas of said segments having various ratios according to the. positive and negative characteristics thereof, means for holding said shaft for oscillation about an axis extending cbllinearly of said shaft, and, a body connected to said shaft to oscillate with said shaft about ai axis.

14. In an oscillator of the torsional type, a torsional element, herefor, comprising an elongated shaft having substantially uniform cross-sectional, area throughout the length of gated shaft having substantially uniform crosssectional area throughout the length of the shaft, and composed or segments ofwhich one segment has a positive temperature coefliclent of thermo-elasticity and the other segment has a, negative temperature coeificient of thermo elasticity, and clamping means secured to the end portions of said shaft, for oscillation about an axis extending collinearly of said shaft, and a body connected to said shaft to oscillate with said shaft about said axis.

16. In an oscillator of the torsional type, a torsional element therefor, comprising an elongated shaft having substantially uniform crosssectional area throughout the length of the shaft, and composed of segments of which one segment has a positive temperature coefficient of thermo-elasticity and the other segment has a negative temperature coefficient of thermoelasticity, and a disc-like mass connected to an intermediate part of said shaft to oscillate about the axis of the shaft, and clamping means se cured to the end portions ofsaid shaft.

BERT'E. ELSENHOUR. 

